The roofs of pitched buildings are often covered with overlapping courses of shingles for protection against the elements. These shingles are typically fastened to the roof with nails or staples which are driven through the shingles and into the roofing subsurface. Over time, the roofing shingles deteriorate and lose their effectiveness, and require periodic removal and replacement.
Hand tools are most commonly used for unfastening and removing such shingles. This manual removal process, however, is tedious, laborious, and exhaustive as it involves one or more roofers who manually and repeatedly insert the tool beneath a free edge of the shingling material and pry upwardly to withdraw the nails from the roof and free the shingles for removal.
Various power tools have been proposed for overcoming the disadvantages of the manual removal process. These known power tools, however, suffer from various deficiencies and are not known to be commonly used.
One of the power tools proposed heretofore is that disclosed in U.S. Pat. No. 4,673,219 which has a power driven rotatable drum equipped with cutting teeth which forcibly cut and remove the shingles as the drum rotates. This removal process, however, is both inefficient and presents a likelihood of causing damage to the roof from the rotating cutting teeth.
U.S. Pat. No. 4,880,491 discloses a shingle removal tool having a reciprocable power driven blade. The reciprocating movements of the blade cannot withdraw the nails from the roof by lifting the shingles, but rather tends to shear the nails leaving the shanks of the nails secured to the roof. The remaining nail shaft then manually must be extracted or driven flush with the surface of the roof in order to avoid damaging the newly applied roofing material.
U.S. Pat. No. 5,009,131 discloses a shingle removal tool having a powered cutting blade which reciprocates sideways in a horizontal plane for the purpose of cutting the nails. As already mentioned, extracting the nails is preferred over shearing them since the latter requires the remaining nail shaft to be dealt with.
Each of U.S. Pat. Nos. 4,663,995; 4,691,439 and 4,763,547 discloses a shingle removing tool having a power driven lifting plate for lifting the shingles and nails from the surface of the roof. Although these devices have the desirable attribute of lifting the shingles and nails for their removal, the blade lifting mechanisms are fairly complex. Further, these devices are not self-propelled but require an operator to push the devices forwardly.